It’s not easy being an app developer. With over a million apps on Google Play, your great idea may become hidden by all of your competitors. You may be looking for some way to differentiate yourself and get ahead, whether that be some promotion or marketing scheme.
However, Google Play has policies around promoting apps while not spamming users. They have just published a few pages pointing out prohibited ways to improve app installs. If your app breaks these policies, you are subject to get your app suspended, losing all potential users.
Many of these policies may be common sense: avoid spamming users, don’t offer incentives to review your app, don’t imply endorsements by other users or apps.
If any of your apps follow these guidelines, you should revise your Play Store listing now to avoid a suspension.